Plural beam electron beam scanner utilizing a modulation grid

ABSTRACT

A plurality of flat coded dynode members are sandwiched between an electron emitting cathode in the form of a flat plate and a flat target plate. Each dynode member has a plurality of apertures formed therein which are aligned with corresponding apertures on all the other dynodes to form an electron beam channel. The dynodes further each have a pair of separate conductive portions thereon arranged in a predetermined finger pattern, the finest of such finger patterns defining an elemental scanning area of the target plate. Each of such basic resolution elements is formed by means of a channel for each of a plurality of scanning beams. A modulation grid having apertures therein corresponding to the apertures on the dynodes and aligned therewith is placed between the cathode and target and is used to control the energization of the beams. A dynode having one of the finest finger patterns thereon has such finger patterns arranged so that each basic scanning element has a single aperture for each of the separate scanning beams, thereby enabling simultaneous scanning over the entire target area for the separate beams.

United States atent 91 McCann [451 Jan. 2, 1973 [54] PLURAL BEAM ELECTRON BEAM SCANNER UTILIZING A MODULATEON GRID [75] Inventor: Farrell A. McCann, Hawthorne,

Primary Examiner--Carl D. Quarforth Assistant ExaminerJ. M. Potenza & Wohlgemuth and W. M.

Attorney-Sokolski Graham [57] ABSTRACT A plurality of flat coded dynode members are sandwiched between an electron emitting cathode in the form of a flat plate and a flat target plate. Each dynode member has a plurality of apertures formed therein which are aligned with corresponding apertures on all the other dynodes to form an electron beam channel. The dynodes further each have a pair of separate conductive portions thereon arranged in a predetermined finger pattern, the finest of such finger patterns defining an elemental scanning area of the target plate. Each of such basic resolution elements is formed by means of a channel for each of a plurality of scanning beams. A modulation grid having apertures therein corresponding to the apertures on the dynodes and aligned therewith is placed between the cathode and target and is used to control the energization of the beams. A dynode having one of the finest finger patterns thereon has such finger patterns arranged so that each basic scanning element has a single aperture for each of the separate scanning beams, thereby enabling simultaneous scanning over the entire target area for the separate beams.

8 Claims, 3 Drawing Figures MODULATOR NO. I

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INVENTOR FARRELL A. M CANN SOKOLSKI 8| WOHLGEMUTH ATTORNEYS PLURAL BEAM ELECTRON BEAM SCANNER UTILIZING A MODULATION GRID This invention relates to an electron beam scanner and more particularly to such a scanner formed by a plurality of flat plate elements which is capable of multiple beam operation.

In U.S. Pat. No. 3,408,532, to D. E. Hultberg et ai.,

assigned to Northrop Corporation, the assignee of the instant application, an electron beam scanner is described utilizing a plurality of coded dynode members sandwiched between an electron emitting cathode and a target plate wherein the dynodes have a pair of separate conductive portions arranged in a finger pattern. The dynode apertures are aligned with each other to define electron beam channels running between the cathode and the target, each of such channels defining a scanning element of the target. The dynode fingers are excited in response to digital control signals to activate one of the channels at a time thereby addressing the beam to activate the target elements in a predesired manner.

The device of this invention involves a modification to the device of the aforementioned patent which enables multibeam operation whereby such beams are excited in response to separate control signals, such as, for example, as utilized for each of the colors in a color television display. It will be appreciated that while the device of the invention is well suited for a color television display, it can also be utilized to equal advantage in other situations where a plurality of display beams are required either operating simultaneously or separately at different times. It is further to be noted that the device of the invention can also be utilized as an image sensor or memory device to sense or memorize a number of separate images or patterns.

The modification of this invention involves a relatively simple implementation using a minimum number of components beyond those required for the single beam scanning of U.S. Pat. No. 3,408,532. The device of this invention thus provides a multiple beam scanner capable of providing a color video display which has all of the advantages of the device of U.S. Pat. No. 3,408,532 over cathode ray tube devices. These attributes include the capability of random addressing to any point on the target without a sacrifice of resolution and speed of operation, a relatively flat compact construction, the capability of high linearity and definition and relative immunity to ambient electrostatic and electromagnetic fields.

It is therefore the principal object of this invention to provide an improved electron beam scanning device of the type described in U.S. Pat. No. 3,408,532, capable of multibeam operation such as that involved in a color video display.

Other objects of this invention will become apparent as the description proceeds in connection with the accompanying drawings, of which:

FIG. 1 is a schematic drawing illustrating a preferred embodiment of the device of the invention,

FIG. 2 is a schematic drawing illustrating the modulation grid of the preferred embodiment, and

FIG. 3 is a schematic drawing illustrating one of the finest finger pattern dynodes of the preferred embodiment.

Briefly described, the device of the invention comprises a flat plate cathode and a flat plate target having a plurality of control plates or dynodes sandwiched therebetween for controlling a plurality of electron beams. It is to be noted that the control plates need not comprise electron multipliers or dynodes. The dynodes have a plurality of apertures formed therein which are aligned with each other to form electron beam channels between the cathode and the target. A plurality of separate scanning beams which may be simultaneously separately modulated are provided by means of a plurality of separate apertures provided in the dynodes for each basic scanning element. The dynodes have control electrodes arranged in a predetermined finger pattern, the finest finger pattern defining a basic target element defining an elemental scanning area on the target. Control switching means are provided for the dynodes to selectively energize the finger pattern electrodes so as to cause a single target scanning element to be ener-- gized at a time. A modulation grid having apertures therein corresponding to those on the control dynodes has control electrodes formed thereon for controlling the electron beams, each of which is included in every one of the target scanning elements.

The disclosure of U.S. Pat. No. 3,408,532 is incorporated herein by reference, and it is to be understood that the drawings and specification of this patent are applicable to the instant disclosure except where specifically modified herein. The disclosure of this application will therefore only include descriptive information necessary to describe the particular new elements and modified elements needed to make for multi-beam operation.

Referring now to FIG. 1, a preferred embodiment of the device of the invention is schematically illustrated. Interposed between cathode l6 and target ll are a plurality of dynode members 19-25. A power source 33 is connected between the cathode and the target to accelerate the flow of electrons therebetween. As described in U.S. Pat. No. 3,408,532, the cathode, target and dynode members are enclosed in a vacuum type environment. The dynodes have a plurality of apertures 47 therein arranged on all of the dynodes in a similar matrix pattern. The dynodes are aligned with each other so that their corresponding apertures are aligned with each other to form electron beam channels between the cathode and the target. Dynode 20 has conductive portions 20a and 20b on the opposite broad surfaces thereof, these conductive portions being insulated from each other and being connected to the opposite stages of flipflop 48. Similarly, dynodes 21-25 have conductive portions 21a, 21b 25a, 25b, respectively, which are connected to corresponding flipflops 49-53.

As fully described in the aforementioned patent, the conductive portions as arranged in the indicated finger patterns are selectively energized to control the electron beam between cathode 16 and target 11 so that a single elemental portion of the target is excited at a time. It is to be noted, however, that in the device of this invention there are three times as many apertures 47 in each of the dynodes as in the device of U.S. Pat. No. 3,408,532, and three times as many electron beam channels thus formed by these apertures. It is also to be noted that for the dynodes 24 and 25 having the finest finger patterns there are double columns and rows of apertures 47 as the case may be for each finger element as compared with only single rows in the aforementioned patent. It is further to be noted that the finger elements of dynode 25 rather than having two straight line edges has one of these edges in a zigzag configuration such that the fingers alternately include one and two apertures. These modifications and the addition of modulation control grid dynode l9 enables the multibeam operation of the device of the invention.

For the purposes of illustration, the finger pattern portions a-25a of the dynodes are shown without stippling to indicate that they are forward biased by their associated flipflops so as to accelerate the electron flow therethrough, while the portions 2017-251) are stippled to indicate that they are back biased. Assuming that the modulation dynode 19 is totally forward biased, it can be seen that only three beams, i.e., 60a, 60b and 600, will-reach target 11. All of the other beams such as, for example, beam 61, are repelled at one or the other of the dynodes. It should be apparent that by appropriate driving of flipflops 48-53, any portion of the target can be energized by the three beams to provide either regular or random scanning.

In the exemplary embodiment, a three beam implementation is shown as could be utilized for a color television display. But, of course, a different number of beams can be provided utilizing the same basic idea set forth herein.

Referring now additionally to FIG. 2, the modulation dynode of the preferred embodiment of the device of the invention is schematically illustrated. Modulation dynode 19 has a plurality of apertures 47 formed therein which are arranged in a matrix pattern to match the apertures on the other dynodes. Conductive strips 70 are deposited on the opposite broad surfaces of dynode 19, these strips being insulated from each other and arranged diagonally so as to encompass diagonal rows of apertures.

Connected to the first, fourth and every succeeding third row of strips 70 thereafter is a modulator 80. Connected to the second, fifth and every succeeding third row of strips 70 thereafter is a modulator 81. Connected to the third, sixth and every succeeding third row of strips thereafter is a modulator 82. Modulators 80-82 are adapted to provide biasing potentials across their associated strips in response to appropriate control signals. These modulators may, for example, operate in response to the three color control signals in a color television receiver. The modulators thus are utilized to modulate the intensity of the beams passing through their associated apertures.

Referring now additionally to FIG. 3, it should be readily apparent that in view of the configuration of the finger patterns a and 25b of dynode 25 that the finger pattern dynodes 20-25, as illustrated in FIG. 11, will pass through to the target all three of the beams (60a, 60b and 600) at a time as modulated by modulators 80-82, thus enabling simultaneous tri-beam display.

It is to be noted that in implementing the device of the invention it is necessary that only one of the finest of the finger patterns, i.e., one of either dynodes 25 (as shown in the illustrative example) or 24, need be arranged in the indicated zigzag pattern so that the 6 dynodes will control all three beams simultaneously. It is also to be noted that in the case of a color television display, target 11 must have its tri-color phosphor dots correlated with the aperture matrix of modulation dynode 19 so that they correspond in position to the associated modulation signals. The three beams, of course, need not be displayed simultaneously and can be used to cover separate display images which are either related or non-related. It is further to be noted that with the channel apertures evenly spaced, as shown in the illustrative embodiment, that in view of the greater number of apertures in one dimension than the other, a rectangular rather than a square display pattern is achieved. In the illustrative example this provides the proper television aspect ratio. However, if a square pattern is desired, this can be achieved by spacing the apertures in one dimension closer together than those in the other.

The device of this invention thus provides simple yet highly effective means for enabling multi-beam operation of an electron beam scanner which is particularly suited to a color video display.

I claim:

1. In an electron beam scanner having a plurality of beams, the number of said beams being n,

a fiat plate cathode,

a flat plate target,

a plurality of control plates sandwiched between said cathode and said target for controlling the flow of electrons therebetween,

each of said control plates having apertures therein, corresponding apertures on said control plates being aligned with each other to form electron channels between the cathode and target,

electrodes arranged on said control plates in predetermined finger pattern pairs,

switch means for alternatively forward biasing one or the other of the finger patterns of each of said pairs to activate a single separate channel for each of said plurality of beams at a time, so as to energize a single target scanning element, and

modulation grid means interposed between said cathode and target for modulating each of said beams, said modulation grid means having a plurality of apertures formed therein corresponding to said control plate apertures and electrode elements arranged in strips on said modulation grid means, each of said strips encompassing a row of said apertures, succeeding nth rows of said strips being connected together, each set of said interconnected strips being used for modulating a separate one of said beams,

at least one of said control plates having its electrodes arranged in a finger pattern finer than those of the other control plates, the finger pattern of said last mentioned control plate being formed such as to delineate said scanning elements.

2. The scanner of claim 1 and additionally including modulation means for providing modulating signals to each of said modulation grid member electrodes.

3. In an electron beam scanner having a plurality of beams,

a flat plate cathode,

a flat plate target,

a plurality of control plates sandwiched between said cathode and said target for controlling the flow of electrons therebetween,

each of said control plates having apertures therein, corresponding apertures on said control plates being aligned with each other to form electron channels between the cathode and target,

from each other, said control plate members further having a plurality of aperture means therein forming channels for the flow of electrons between said cathode and said target members,

electrodes arranged on said control plates in 5 corresponding aperture means of said control predetermined finger pattern pairs, plate members being aligned with each other,

switch means for alternatively forward biasing one or control means for selectively applying an electron the other of the finger patterns of each of said pairs accelerating potential to at least one of the finger to activate a single separate channel for each of portions of each of said control plate members and said plurality of beams at a time, so as to energize a 10 a potential for preventing the flow of electrons to single target scanning element, and the others of the finger portions of each of said modulation grid means interposed between said members,

cathode and target for modulating each of said a modulation grid member interposed between said beams, said modulation grid means having a plucathode and target members and aligned rality of apertures formed therein corresponding therewith, said modulation grid member having a to said control plate apertures and electrode elements arranged in strips on said modulation grid plurality of apertures formed therein corresponding to and aligned with corresponding apertures in said control late members, a least one 0 said control plate members having finger patterns finer than those of any of the others of said control plate members and arranged in a zig-zag configuration, and having groups of apertures, each of said aperture groups defining an ele mental scanning area,

said modulation grid member having electrode ele ments, each of said elements controlling one of the plural beams by controlling the flow of electrons through predetermined ones of said modulation grid apertures, and

modulation means for providing separate modulation signals to predetermined ones of said modulation grid member electrodes,

each elemental target scanning area receiving each of said beams as modulated by said modulation means, each of said strips encompassing a row of said apertures, succeeding third rows of said strips being connected together, each set of said interconnected strips being used for modulating a separate one of said beams,

a least one of said control plates having its electrodes arranged in a finger pattern finer than those of the other control plates, the finger pattern of said last mentioned control plate being formed such as to delineate said target scanning elements.

4. The scanner of claim 1 wherein there are three beams, said one of said control plates having its electrodes in a zig-zag patternso as to alternately encompass one and two dynode apertures, three electron channels being activated at a time to activate a single target scanning element.

5. A plural beam electron beam scanner comprising:

a flat cathode member for emitting electrons, grid member' a target member mounted opposite Said cathode 6. The scanner of claim 5 wherein there are three member beams, the zig-zag pattern alternatively encompassing one and two aperture means.

7. The scanner of claim 6 wherein the electrode elements of said modulation grid member are arranged in strips, each of such strips running diagonally across a row of the apertures of said grid member.

8. The scanner of claim 7 wherein succeeding fourth electrode element strips are connected together, each set of interconnected strips forming one of said electrode elements.

a power source connected between said target member and said cathode member for providing an electron accelerating potential therebetween,

a plurality of control plate members sandwiched between said cathode and target members for controlling the flow of electrons therebetween, said control plate members being aligned opposite each other and said cathode and target members, said control plate members having a plurality of conductive coded finger portions which are insulated 

1. In an electron beam scanner having a plurality of beams, the number of said beams being ''''n,'''' a flat plate cathode, a flat plate target, a plurality of control plates sandwiched between said cathode and said target for controlling the flow of electrons therebetween, each of said control plates having apertures therein, corresponding apertures on said control plates being aligned with each other to form electron channels between the cathode and target, electrodes arranged on said control plates in predetermined finger pattern pairs, switch means for alternatively forward biasing one or the other of the finger patterns of each of said pairs to activate a single separate channel for each of said plurality of beams at a time, so as to energize a single target scanning element, and modulation grid means interposed between said cathode and target for modulating each of said beams, said modulation grid means having a plurality of apertures formed therein corresponding to said control plate apertures and electrode elements arranged in strips on said modulation grid means, each of said strips encompassing a row of said apertures, succeeding ''''nth'''' rows of said strips being connected together, each set of said interconnected strips being used for modulating a separate one of said beams, at least one of said control plates having its electrodes arranged in a finger pattern finer than those of the other control plates, the finger pattern of said last mentioned control plate being formed such as to delineate said scanning elements.
 2. The scanner of claim 1 and additionally including modulation means for providing modulating signals to each of said modulation grid member electrodes.
 3. In an electron beam scanner having a plurality of beams, a flat plate cathode, a flat plate target, a plurality of control plates sandwiched between said cathode and said target for controlling the flow of electrons therebetween, each of said control plates having apertures therein, corresponding apertures on said control plates being aligned with each other to form electron channels between the cathode and target, electrodes arranged on said control plates in predetermined finger pattern pairs, switch means for alternatively forward biasing one or the other of the finger patterns of each of said pairs to activate a single separate channel for each of said plurality of beams at a time, so as to energize a single target scanning element, and modulation grid means interposed between said cathode and target for modulating each of said beams, said modulation grid means having a plurality of apertures formed therein corresponding to said control plate apertures and electrode elements arranged in strips on said modulation grid means, each of said strips encompassing a row of said apertures, succeeding third rows of said strips being connected together, each set of said interconnected strips being used for modulating a separate one of said beams, a least one of said control plates having its electrodes arranged in a finger pattern finer than those of the other control plates, the finger pattern of said last mentioned control plate being formed such as to delineate said target scanning elements.
 4. The scanner of claim 1 wherein there are three beams, said one of said control plates having its electrodes in a zig-zag pattern so as to alternately encompass one and two dynode apertures, three electron channels being activated at a time to activate a single target scanning element.
 5. A plural beam electron beam scanner comprising: a flat cathode member for emitting electrons, a target member mounted opposite said cathode member, a power source connected between said target member and said cathode member for providing an electron accelerating potential therebetween, a plurality of control plate members sandwiched between said cathode and target members for controlling the flow of electrons therebetween, said control plate members being aligned opposite each other and said cathode and target members, said control plate members having a plurality of conductive coded finger portions which are insulated from each other, said control plate members further having a plurality of aperture means therein forming channels for the flow of electrons between said cathode and said target members, corresponding aperture means of said control plate members being aligned with each other, control means for selectively applying an electron accelerating potential to at least one of the finger portions of each of said control plate members and a potential for preventing the flow of electrons to the others of the finger portions of each of said members, a modulation grid member interposed between said cathode and target members and aligned therewith, said modulation grid member having a plurality of apertures formed therein corresponding to and aligned with corresponding apertures in said control plate members, a least one of said control plate members having finger patterns finer than those of any of the others of said control plate members and arranged in a zig-zag configuration, and having groups of apertures, each of said aperture groups defining an elemental scanning area, said modulation grid member having electrode elements, each of said elements controlling one of the plural beams by controlling the flow of electrons through predetermined ones of said modulation grid apertures, and modulation means for providing separate modulation signals to predetermined ones of said modulation grid member electrodes, each elemental target scanning area receiving each of said beams as modulated by said modulation grid member.
 6. The scanner of claim 5 wherein there are three beams, the zig-zag pattern alternatively encompassing one and two aperture means.
 7. The scanner of claim 6 wherein the electrode elements of said modulation grid member are arranged in strips, each of such strips running diagonally across a row of the apertures of said grid member.
 8. The scanner of claim 7 wherein succeeding fourth electrode element strips are connected together, each set of interconnected strips forming one of said electrode elements. 